A Wide‐Range Rising Column Capillary Viscometer for Polymer Melts and Concentrated Solutions

1968 ◽  
Vol 12 (4) ◽  
pp. 573-585
Author(s):  
John H. Elliott
Keyword(s):  
Polymer Melts ◽  
Capillary Viscometer ◽  
Concentrated Solutions ◽  
Wide Range

On the Extensional Rheology of Polymer Melts and Concentrated Solutions

2013 ◽  
Vol 47 (1) ◽  
pp. 379-386 ◽  
Author(s):  
T. Sridhar ◽  
Mohini Acharya ◽  
D. A. Nguyen ◽  
P. K. Bhattacharjee
Keyword(s):  
Polymer Melts ◽  
Extensional Rheology ◽  
Concentrated Solutions

A Numerical Approach for the Evaluation of a Capillary Viscometer Experiment

2018 ◽  
Author(s):  
Felix Fischer ◽  
Julian Bartz ◽  
Katharina Schmitz ◽  
Ludwig Brouwer ◽  
Hubert Schwarze
Keyword(s):  
Pressure Difference ◽  
Cfd Simulation ◽  
Polymer Melts ◽  
Capillary Flow ◽  
Input Parameter ◽  
Numerical Approach ◽  
Capillary Viscometer ◽  
Inlet Section ◽  
Arbitrary Geometries ◽  
Poiseuille Equation

The dynamic viscosity of a fluid is an important input parameter for the investigation of elastohydrodynamic contacts within tribological simulation tools. In this paper, a capillary viscometer is used to analyse the viscosity of a calibration fluid for diesel injection pumps. Capillary viscometers are often used for the determination of viscosities that show a significant dependence on shear rate, pressure and temperature such as polymer melts or blood. Therefore most of the research on corrections of measured viscosities have been made using polymer melts. A new method is presented to shorten the effort in evaluating the capillary experiment. The viscosity itself can be calculated from experimental data. Essential parameters are the radius of the capillary, its length, the capillary flow and the pressure difference over the capillary. These quantities are used in the Hagen-Poiseuille equation to calculate the viscosity, assuming laminar and monodirectional flow. According to said equation, the viscosity depends on the geometry and the pressure gradient. A typical capillary viscometer contains three main flow irregularities. First the contraction of the flow at the capillary inlet, second the expansion of the flow at the capillary outlet and third the inlet section length of the flow after which the velocity profile is fully developed. These flow phenomena cause pressure losses, which have to be taken into account, as well as the altered length of the laminar flow in the capillary. Furthermore, the temperature difference over the capillary also affects the outlet flow. Therefore, in this paper, a newly developed method is proposed, which shortens the effort in pressure and length correction. The method is valid for viscometers, which provide a single phase flow of the sampling fluid. Furthermore, the proposed correction is suited for arbitrary geometries. A numerical approach is chosen for the analysis of the experiment. In order to facilitate the experimental procedure of a capillary viscometer, a special algorithm was developed. The numerical approach uses a static CFD simulation, which is recursively passed through. If a termination condition, regarding the pressure difference between two cycles, is fulfilled, the real viscosity can be calculated in the usual way from the Hagen-Poiseuille equation. A special advantage of the proposed experimental evaluation is the general applicability for arbitrary geometries. In this paper, the procedure is validated with a well-known reference fluid and compared to data, which was gathered from a quartz viscometer experiment with the same fluid. Therefore, experiments are conducted with the capillary viscometer and compared at various pressure and temperature levels.

A small scale capillary viscometer for polymer melts

1969 ◽  
Vol 8 (2) ◽  
pp. 226-229
Author(s):  
N. J. Mills
Keyword(s):  
Polymer Melts ◽  
Small Scale ◽  
Capillary Viscometer

Rheology of blood

1962 ◽  
Vol 202 (6) ◽  
pp. 1188-1194 ◽  
Author(s):  
L. C. Cerny ◽  
F. B. Cook ◽  
C. C. Walker
Keyword(s):  
Shape Factor ◽  
Flow Behavior ◽  
Flow Equation ◽  
Capillary Viscometer ◽  
Shear Stresses ◽  
Red Cell ◽  
Newtonian Flow ◽  
Wide Range ◽  
Citrate Dextrose

The non-Newtonian flow properties of resuspended red cells were determined in vitro by means of a capillary viscometer. In order to evaluate the rheological effect of the suspending medium, viscosity measurements were made over a wide range of shearing stresses using both plasma and an acid-citrate-dextrose solution as diluents. At low shearing stresses, the plasma exhibited non-Newtonian flow behavior. Using a technique of treating the data to obtain rate-of-shear versus shearing-stress curves without prior assumption of a flow equation showed that whole blood over a wide range of shear stresses and a twofold range of capillary radii did not show any dependence of the viscosity on the capillaries employed. This procedure was also used to examine the data of other workers. In an attempt to determine the shape factor for the red cell, an extrapolation to infinite dilution and zero rate of shear was made. The shape factor can be estimated to be 2.5±1.5 for red cell.

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